1. Field of the Invention
The present invention relates to solar cell materials. More particularly, the present invention relates to an organic dye used in a dye-sensitized solar cell.
2. Description of the Related Art
The demand for energy conservation triggered the search for alternate renewable energy sources. A practical solution is the adoption of light-harvesting biological concepts. This biomimetic strategy has been recently translated into technological advances such as solar cells. Although silicon-based semiconductors dominated solar cell applications for decades, recent demonstration of dye-sensitized solar cells (DSSCs) based on nano-crystalline TiO2 by Grätzel et al. (e.g., O'Regan, B.; Grätzel, M. Nature 1991, 353, 737) opened up the opportunity for organic and organometallic dyes in this area. A dye with excellent light-absorbing capability in the red and near-IR region, photostability, and redox stability is attractive for the functioning of DSSCs.
Coumarin-, indoline-, cyanine-, and hemicyanine based dyes have been used for the construction of DSSCs recently. However, the performances of DSSCs based on these large molecules are usually insufficient. On the other hand, though polymers based on small chromophoric groups like benzothiadiazole group have been employed in photovoltaic applications (e.g., van Duren, J. K. J.; Dhanabalan, A.; van Hal, P. A.; Janssen, R. A. J. Synth. Metals 2001, 121, 1587), small molecules containing such small chromophoric groups are never exploited for DSSCs.